Radio frequency communication devices and methods

1. A radio frequency (RF) communication device to transmit or receive data over a plurality of frequencies, comprising:

a coupler having a plurality of ports; and

an adjustable termination coupled to a first of the plurality of ports;

a memory configured to store a plurality of pre-determined termination values corresponding to the plurality of communication frequencies, respectively, and

a controller configured to determine a communication frequency to be used after the pre-determined termination values are stored in memory, and further configured to look-up a pre-determined termination value corresponding to the communication frequency to be used, wherein the controller is further configured to provide a first control signal to adjust an impedance of the adjustable termination based on the looked-up pre-determined termination value.

2. The RF communication device of claim 1 , wherein the communication frequency comprises a transmission frequency at which the communication device transmits data over an antenna.

3. The RF communication device of claim 2 , further comprising:

a power amplifier associated with an input port of the coupler; and

a switchplexer associated with a transmission port of the coupler and adapted to selectively couple the transmission port to the antenna.

4. The RF communication device of claim 3 , where the first port to which the adjustable termination is coupled is an isolation port of the coupler.

5. The RF communication device of claim 3 , further comprising:

a power detector associated with a coupled port of the coupler.

6. The RF communication device of claim 5 ,

wherein the controller is adapted to provide a second control signal to the power amplifier based on feedback from the power detector.

7. The RF communication device of claim 1 , wherein the adjustable termination further comprises:

an adjustable capacitor that is adjustable based on the communication frequency.

8. The RF communication device of claim 7 , further comprising:

an adjustable resistor in series with the adjustable capacitor and adjustable based on the communication frequency.

9. The RF communication device of claim 1 , where the adjustable termination comprises: an adjustable transmission line that is adjustable based on the communication frequency.

10. A radio frequency (RF) communication device, comprising:

a power amplifier adapted to receive a signal-of-interest and deliver an amplified signal based on the signal-of-interest;

a coupler comprising: an input port adapted to receive the amplified signal, a transmission port adapted to provide a transmitted signal based on the amplified signal, and an isolated port associated with an adjustable complex termination;

a memory configured to store a plurality of pre-determined termination values corresponding to a plurality of operating conditions, respectively, and

a controller configured to determine an operating condition of the RF communication device after the pre-determined termination values are stored in memory, wherein the operating condition corresponds to at least one of: the transmission frequency, a transmission path to be used, a temperature, or a state of user interaction with the phone;

wherein the controller is further configured to lookup a pre-determined termination value from the memory based on the operating condition and provide a control signal to adjust an impedance of the adjustable complex termination based on the looked-up pre-determined termination value.

11. The RF communication device of claim 10 , further comprising:

a switchplexer adapted to selectively pass the transmitted signal to an antenna associated with the communication device.

12. The RF communication device of claim 11 , wherein the adjustable termination is adjustable to account for different paths between the power amplifier and the antenna.

13. The RF communication device of claim 10 , where the controller is further adapted to monitor power at a coupled port of the coupler and provide feedback to the power amplifier to adjust the amplified signal.

14. The RF communication device of claim 10 , wherein the power amplifier is associated with a plurality of pins and a different control signal associated with the power amplifier is transmitted over each pin.

15. The RF communication device of claim 10 , wherein the power amplifier includes a set of registers associated with a serial interface.

16. The RF communication device of claim 15 , wherein the power amplifier is adapted to receive control signals over the serial interface as datagrams, wherein the datagrams include a bit field associated with pre-determined R/C values for the adjustable termination.

17. A method for efficiently transmitting power to an antenna, comprising:

determining a first transmission frequency;

setting an adjustable termination at a first port of a coupler to a first predetermined value based on the transmission frequency;

transmitting a first outgoing radio-frequency (RF) signal over an antenna at the first transmission frequency while the adjustable termination is set to the first predetermined value;

determining a second, different transmission frequency;

setting the adjustable termination to a second, different predetermined value based on the second transmission frequency; and

transmitting a second outgoing radio-frequency (RF) signal over the antenna at the second transmission frequency while the adjustable termination is set to the second predetermined value.

18. The method of claim 17 , where transmitting the first outgoing RF signal comprises:

receiving a signal-of-interest and generating an amplified signal therefrom, where the amplified signal includes components at the first transmission frequency;

providing the amplified signal to an input port of the coupler; and

adjusting the amplified signal while the adjustable termination is set to the first predetermined value to efficiently transmit power to the antenna.

19. The method of claim 18 , where transmitting the first outgoing RF signal further comprises:

measuring a coupled signal at a coupled port of the coupler;

adjusting the amplified signal to keep the coupled signal approximately constant; and

altering a termination at another port of the coupler based on an operating condition to efficiently transmit power to the antenna.

20. A method for efficiently transmitting power to an antenna, comprising:

receiving a signal of interest and generating an amplified signal therefrom, where the amplified signal includes components at a transmission frequency;

cooperatively adjusting the amplified signal and an adjustable termination at a port of a coupler based on the transmission frequency;

transmitting an outgoing radio-frequency (RF) signal over an antenna at the transmission frequency;

determining another transmission frequency; and

cooperatively adjusting the amplified signal and the adjustable termination based on the another transmission frequency.

21. The method of claim 20 , where the signal of interest comprises a baseband signal and the amplified signal comprises a modulated signal based on the baseband signal.

22. A radio frequency (RF) communication device, comprising:

a power amplifier including a set of registers associated with a serial interface and adapted to receive a signal-of-interest and deliver an amplified signal based on the signal-of-interest;

a coupler comprising: an input port adapted to receive the amplified signal, a transmission port adapted to provide a transmitted signal based on the amplified signal, and an isolated port associated with an adjustable complex termination that is adjustable based on an operating condition of the RF communication device;

wherein the power amplifier is adapted to receive control signals over the serial interface as datagrams, wherein the datagrams include a bit field associated with pre-determined R/C values for the adjustable termination.

23. A radio frequency (RF) communication device, comprising:

a coupler comprising first and second transmission lines and having a plurality of ports coupled to respective ends of the first and second transmission lines; and

an adjustable termination coupled to a first of the plurality of ports and adjustable based on a dynamic operating condition of the RF communication device, wherein the first port is coupled to an end of the first transmission line;

an adjustable phase shifter coupled to a second of the plurality of ports, wherein the second port is coupled to an end of the second transmission line.